ASP.NET

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    //open database connection..
    SqlConnection QADatabase = new SqlConnection();
    QADatabase.ConnectionString = SqlDataSource1.ConnectionString;
    QADatabase.Open();

    //find the records I need to put in the second DropDownList.
    SqlCommand command = new SqlCommand("SELECT Machines FROM Machines WHERE DeptID=" + DropDownList1.SelectedIndex ,QADatabase);

    SqlDataReader reader = command.ExecuteReader();
    while (reader.Read())
    {
        //Add the items to DropDownList..
        DropDownList2.Items.Add((string)reader["Machines"]);
        //Refresh panel..
        UpdatePanel1.Update();
    }
    QADatabase.Close();
}